Tun Seng Herng

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Coexistence of polarization and resistance-switching characteristics in single compounds has been long inspired scientific and technological interests. Here, we report the non-volatile resistance change in noncentrosymmetric compounds investigated by using defect nanotechnology and contact engineering. Using a noncentrosymmetric material of ZnO as example,(More)
The ferromagnetism in many carbon nanostructures is attributed to carbon dangling bonds or vacancies. This provides opportunities to develop new functional materials, such as molecular and polymeric ferromagnets and organic spintronic materials, without magnetic elements (for example, 3d and 4f metals). Here we report the observation of room temperature(More)
The bipolar charge phenomenon in Cu and Co co-doped zinc oxide (ZnO) film samples has been studied using scanning probe microscopy (SPM) techniques. Those ZnO samples are made using a pulsed laser deposition (PLD) technique. It is found that the addition of Cu and Co dopants suppresses the electron density in ZnO and causes a significant change in the work(More)
We report direct evidence of room-temperature ferromagnetic ordering in O-deficient ZnO:Cu films by using soft x-ray magnetic circular dichroism and x-ray absorption. Our measurements have revealed unambiguously two distinct features of Cu atoms associated with (i) magnetically ordered Cu ions present only in the oxygen-deficient samples and (ii)(More)
www.MaterialsViews.com C O M M U N IC A IO N Tun Seng Herng , Meng Fei Wong , Dongchen Qi , Jiabao Yi , Amit Kumar , Alicia Huang , Fransiska Cecilia Kartawidjaja , Serban Smadici , Peter Abbamonte , Cecilia Sánchez-Hanke , Santiranjan Shannigrahi , Jun Min Xue , John Wang , Yuan Ping Feng , Andrivo Rusydi , * Kaiyang Zeng,* and Jun Ding * Mutual(More)
Extended bis(benzothia)quinodimethanes and their dications were synthesized as stable species. The neutral compounds mainly have a quinoidal structure in the ground state but show increased diradical character with extension of the central quinodimethane unit. The dications exhibit similar electronic absorption spectra, NMR spectra, NICS values, and(More)
Radical cations and dications of π-conjugated systems play vital roles in organic electronic devices, organic conductors, and conducting polymers. Their structures, charge and spin distribution, and mechanism of charge transport are of great interest. In this article, radical cations and dications of a series of newly synthesized methylthio-capped rylenes(More)
Superbenzoquinone (SBQ) is a quinone derived from a classic polycyclic aromatic hydrocarbon (PAH), hexa-peri-hexabenzocoronene (so-called "superbenzene"), and is a challenging synthetic target. Herein we report the successful synthesis and characterization of its derivatives. We reveal that the high reactivity of SBQ is due to its intrinsic open-shell(More)
Chichibabin's and Müller's hydrocarbons are classical open-shell singlet diradicaloids but they are highly reactive. Herein we report the successful synthesis of their respective stable analogues, OxR-2 and OxR-3, based on the newly developed oxindolyl radical. X-ray crystallographic analysis on OxR-2 reveals a planar quinoidal backbone similar to(More)
The fundamental relationship between structure and diradical character is important for the development of open-shell diradicaloid-based materials. In this work, we synthesized two structural isomers bearing a 2,6-naphthoquinodimethane or a 1,5-naphthoquinodimethane bridge and demonstrated that their diradical characters and chemical reactivity are quite(More)